From: Alistair Popple <apopple@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: <linux-mm@kvack.org>, <nouveau@lists.freedesktop.org>,
<bskeggs@redhat.com>, <akpm@linux-foundation.org>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<kvm-ppc@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
<jhubbard@nvidia.com>, <rcampbell@nvidia.com>,
<jglisse@redhat.com>, <jgg@nvidia.com>, <daniel@ffwll.ch>,
<willy@infradead.org>
Subject: Re: [PATCH v6 8/8] nouveau/svm: Implement atomic SVM access
Date: Mon, 22 Mar 2021 20:27:33 +1100 [thread overview]
Message-ID: <6407817.nLXe9rGL3b@nvdebian> (raw)
In-Reply-To: <20210315075113.GD4136862@infradead.org>
On Monday, 15 March 2021 6:51:13 PM AEDT Christoph Hellwig wrote:
> > - /*XXX: atomic? */
> > - return (fa->access == 0 || fa->access == 3) -
> > - (fb->access == 0 || fb->access == 3);
> > + /* Atomic access (2) has highest priority */
> > + return (-1*(fa->access == 2) + (fa->access == 0 || fa->access == 3)) -
> > + (-1*(fb->access == 2) + (fb->access == 0 || fb->access == 3));
>
> This looks really unreabable. If the magic values 0, 2 and 3 had names
> it might become a little more understadable, then factor the duplicated
> calculation of the priority value into a helper and we'll have code that
> mere humans can understand..
Fair enough, will add some definitions for the magic values.
> > + mutex_lock(&svmm->mutex);
> > + if (mmu_interval_read_retry(¬ifier->notifier,
> > + notifier_seq)) {
> > + mutex_unlock(&svmm->mutex);
> > + continue;
> > + }
> > + break;
> > + }
>
> This looks good, why not:
>
> mutex_lock(&svmm->mutex);
> if (!mmu_interval_read_retry(¬ifier->notifier,
> notifier_seq))
> break;
> mutex_unlock(&svmm->mutex);
> }
I had copied that from nouveau_range_fault() but this suggestion is better.
Will update, thanks for looking.
prev parent reply other threads:[~2021-03-22 9:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 8:38 [PATCH v6 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-03-12 8:38 ` [PATCH v6 1/8] mm: Remove special swap entry functions Alistair Popple
2021-03-15 7:27 ` Christoph Hellwig
2021-03-22 9:20 ` Alistair Popple
2021-03-12 8:38 ` [PATCH v6 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-03-12 8:38 ` [PATCH v6 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-03-15 7:28 ` Christoph Hellwig
2021-03-12 8:38 ` [PATCH v6 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-03-12 8:38 ` [PATCH v6 5/8] mm: Device exclusive memory access Alistair Popple
2021-03-15 7:42 ` Christoph Hellwig
2021-03-22 10:27 ` Alistair Popple
2021-03-12 8:38 ` [PATCH v6 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-03-12 8:38 ` [PATCH v6 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-03-12 8:38 ` [PATCH v6 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
2021-03-15 7:51 ` Christoph Hellwig
2021-03-22 9:27 ` Alistair Popple [this message]
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